Try this
Drag any orange dot to resize the parallelogram. The perimeter is calculated as you drag.
Drag point D to change the base length.

How to find the perimeter of a parallelogram

Like any polygon, the perimeter is the total distance around the outside,
which can be found by adding together the length of each side.
In the case of a parallelogram, each pair of opposite sides is the same length,
so the perimeter is twice the base plus twice the side length. Or as a formula: